1. Field of the Invention
The present invention relates to a navigation server and the like which supports a guidance of a mobile object guided by a navigation apparatus on the basis of communication with the navigation apparatus.
2. Description of the Related Art
There has been used proposed a system which analyses data (FCD) about positional information and the like collected by a floating car (or a probe car) and uses the analysis result thereof to support smooth driving of plural vehicles. Moreover, there has been proposed a method of providing traffic information per divergent direction at a node such as an intersection to a navigation apparatus (refer to Japanese Patent Laid-open No. 2005-283480).
At a node with at least three links intersected, when a user transits from one link to another link, the movement cost varies in accordance with traffic conditions around the node. For example, when an antecedent vehicle Q1 and a subsequent vehicle Q2 are facing a heavy traffic on the oncoming lane at a node where a first link and a prior link are intersected as illustrated in FIG. 5(a), it is hard for the antecedent vehicle Q1 to turn right and it is hard for the subsequent vehicle Q2 to advance smoothly due to the antecedent vehicle Q1. In this situation, transition costs from the prior link to the first and second links, respectively, become higher. On the other hand, as illustrated in FIG. 5(b), when the antecedent vehicle Q1 and the subsequent vehicle Q2 are facing a light traffic on the oncoming lane at the same node, the vehicle Q1 can make a right turn immediately, and the vehicle Q2 is not obstructed by a vehicle in the front, thus, it can advance smoothly. In this situation, the transition costs from the prior link to the first and the second links, respectively, are lower. Moreover, when there are two lanes in the prior link for diverging vehicles to the first and second links, respectively, even though the vehicle Q1 is hard to make a right turn as mentioned above, the vehicle Q2 can transit to the second link regardless of the vehicle Q1, the transition cost from the prior link to the first link is high, however, the transition cost from the prior link to the second link is low.
Thereby, when the transition cost from one link to each of the other links is not accurately evaluated, the overall evaluation on the movement cost for the user to move from plural links may deviate from the real traffic conditions, and further the guiding behavior of the user may become inappropriate from the viewpoint of movement cost.